Internal architecture process when publishing and accessing reports in the cloud

Dear all,

Could you point me to some documentation or recommend some books regarding the internal architecture and the internal process power BI takes when we publish reports from desktop to service or when someone tries to access the reports in the cloud via a web browser?

Edit: I don't mean the storage engine and formula engine that comes into play after ReportDefinition and dataset are loaded into memory. I mean the process it takes like which process handles authentication, which process sends report definition to azure SQL under the hood and which process sends dataset into azure blob and so on?